Motion estimation apparatus, method, and machine-readable medium capable of detecting scrolling text and graphic data

ABSTRACT

A motion estimation apparatus, method, and machine-readable medium capable of detecting scrolling text or graphic data, which can provide information of whether text or graphic data scrolling in a horizontal direction on a screen exists and information related thereto.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Application No.10-2002-73330, which was filed on Nov. 23, 2002, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a motion estimation apparatus and amethod thereof, and, more particularly, to a motion estimation apparatusand a method thereof capable of detecting scrolling text and graphicdata in a horizontal direction on a screen.

2. Description of the Related Art

There exist the interlaced scan mode and the progressive scan mode forscan modes for a video display device. The interlaced scan mode is usedfor general TVs and so on, and refers to a mode that, when one image isdisplayed, divides one frame image into two fields and sequentiallydisplays the two fields one after the other, whereas the progressivescan mode is used for computer monitors, digital TVs, and so on, andrefers to a mode that displays at a time entire frames with one imageframe processed as a unit frame just like a film is projected on ascreen.

As more video display devices of progressive scan mode are used and, atthe same time, the necessity of data exchanges among devices usingdifferent scan modes grows, the importance is placed more than everbefore on the interlaced-to-progressive conversion (IPC) method thatconverts the interlaced scan mode into the progressive scan mode.Therefore, IPC methods having a far more enhanced performance arerequired to obtain images of better quality.

There exist diverse methods for interlaced-to-progressive conversions.As basic methods, there are an intra-field IPC method that insertsaverage data of two-line data between two lines of a current field toimplement a new field, and an inter-field IPC method having no motioncompensation that inserts between lines of a current field average dataof data ahead of and behind the current field to implement one frame.Such IPC methods are easily implemented, but cannot achieve asatisfactory image quality. Accordingly, a motion-compensated IPC methodhas been proposed that divides an image into plural blocks with respectto time-continuous field data with reference to current field data,obtains motions for the respective blocks, and interpolates a currentframe image with reference to vectors of the motions. A motion-adaptiveIPC method has been also proposed that estimates the extent of motionsand interpolates frames based on the motions, and so on. Such IPCmethods can obtain an image quality better than the basic methods, buthave relatively more complicated hardware.

However, the IPC methods are not suitable for displays of text orgraphic data such as news, programs, stock prices, whether, and so on,with horizontal scrolling at the bottom of a screen, and so on. That is,due to the characteristics of scrolling text or graphic data, in casethat the intra-field IPC method or the intra-field IPC method is used,text in interpolated images is not clearly displayed, and displaysbroken letters on many occasions. Further, in case of scrolling text orgraphic data, because plural lines move on the screen in the horizontaldirection at a certain speed, image interpolations can be easilyimplemented if there is information of whether scrolling text or graphicdata exists and a scrolling speed, so that excellent imageinterpolations in terms of performance or speed become possible withoutthe use of a complicated algorithm such as the motion-compensated IPCmethod or the motion-adaptive IPC method.

Therefore, a motion estimation apparatus and a method applicable to IPCmethods and the like become necessary for detecting whether text orgraphic data scrolling in the horizontal direction of a screen existsand proving information necessary for image interpolations.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to provide amotion estimation apparatus and a method capable of detecting whethertext or graphic data scrolling in the horizontal direction of a screenexists, and providing information necessary for image interpolations.

Additional aspects and advantages of the invention will be set forth inpart in the description which follows and, in part, will be obvious fromthe description, or may be learned by practice of the invention.

In order to achieve the above aspect, a motion estimation apparatusaccording to the present invention comprises a line-wise motionestimation unit for calculating motion vectors indicating the extent ofmotions in a horizontal direction for individual lines of apredetermined search area with reference to a current field/frame and areference field/frame; a motion vector buffer for storing motion vectorsfor the individual lines; a scroll detection unit for determiningwhether scroll motions exist in the current field/frame based on themotion vectors for the individual lines which are stored in the motionvector buffer; and a scroll line detection unit for determining whetherthe scroll motions exist in the individual lines of the search area,based on a result of the determination of the scroll detection unit.

The line-wise motion estimation unit includes a pixel buffer forsequentially storing pixel data constructing lines to calculate themotion vectors in the reference field/frame; a FIFO buffer forsequentially storing pixel data constructing lines to calculate themotion vectors in the current field/frame; an SAD buffer for calculatingand storing summed absolute difference (SAD) values based on estimationsof the extent of motions, using the pixel data respectively stored inthe pixel buffer and the FIFO buffer; and a motion vector estimator forcalculating the motion vectors based on the SAD values stored in the SADbuffer. In here, it is possible that the motion vector estimatorcalculates the motion vectors in correspondence to a motion estimationposition having the minimum value of the SAD values stored in the SADbuffer.

The motion estimation apparatus further comprises a motion detector fordetermining the validity of the motion vectors calculated by the motionvector estimator; and an output selector for selectively outputting onlyselected motion vectors based on a result of the validity decision ofthe motion detector. At this time, the motion estimator determines thatthe motion vectors are valid if a difference between the maximum valueand the minimum value of the SAD values stored in the SAD buffer islarger than a predetermined threshold value.

The scroll detection unit calculates the number of occurrences bymagnitudes of the motion vectors stored in the motion vector buffer, anddetermines that the scroll motions exist when motion vectors of certainmagnitudes are determined to be more than the predetermined number ofoccurrences. Further, the scroll line detection unit may decide that thescroll motions exist in corresponding lines when motion vectorscalculated line by line correspond to the magnitudes of motion vectorsare determined to be more than the predetermined number of occurrences.

In the meantime, a motion estimation method according to the presentinvention comprises (a) calculating motion vectors indicating the extentof motions in a horizontal direction for individual lines of apredetermined search area with reference to a current field/frame and areference field/frame; (b) storing motion vectors for the individuallines; (c) determining whether scroll motions exist in the currentfield/frame based on the stored motion vectors for the individual lines;and (d) determining whether the scroll motions exist in the individuallines of the search area, based on a result of the decision of thestep(c).

Operation (a) further comprises (a1) sequentially storing pixel dataconstructing lines to calculate the motion vectors in the referencefield/frame; (a2) sequentially storing pixel data to calculate themotion vectors in the current field/frame; (a3) calculating and storingsummed absolute difference(SAD) values based on estimations of theextent of motions, using the pixel data respectively stored inoperations(a1) and (a2); and (a4) calculating the motion vectors basedon the stored SAD values. In here, it is possible that operation(a4)calculates the motion vectors in correspondence to a motion estimationposition having the minimum value of the stored SAD values.

The motion estimation method further comprises determining the validityof the motion vectors calculated in operation(a4); and selectivelyoutputting only valid motion vectors based on a result of the validitydetermination. At this time, the determining the validity determines themotion vectors as valid if a difference between the maximum value andthe minimum value of the SAD values stored in the SAD buffer is largerthan a predetermined threshold value.

Operation (c) calculates the number of occurrences by magnitudes of thestored motion vectors, and determines that the scroll motions exist whenmotion vectors of certain magnitudes are determined to be more than thepredetermined number of occurrences. Further, operation(d) maydetermines that the scroll motions exist in corresponding lines aredetermined to be motion vectors calculated line by line corresponds tothe magnitudes of motion vectors detected more than the predeterminednumber of occurrences.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and/or advantages of the present invention willbecome apparent and more readily appreciated from the followingdescription of the preferred embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 is a block diagram for showing a motion estimation apparatus,according to an embodiment of the present invention;

FIG. 2 is a block diagram for showing a line-wise motion estimation unitof FIG. 1; and

FIG. 3 is a flow chart for explaining an operation process for a motionestimation apparatus, according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout.

FIG. 1 is a block diagram for showing a motion estimation apparatusaccording to an embodiment of the present invention. The motionestimation apparatus includes a line-wise motion estimation unit 100, ademultiplexer 150, a motion vector buffer 200, a scroll detection unit250, a scroll line detection unit 300, and a multiplexer 350.

The line-wise motion estimation unit 100 calculates motion vectorsindicating motions in a horizontal direction with reference to lines ofinputted reference field/frame and current field/frame. In here, thereference field/frame denotes a reference field or a reference frame,and the current field/frame denotes a current field or a current frame.

The motion vector buffer 200 stores motion vectors estimated in theline-wise motion estimation unit 100 with respect to individual lines.At this time, the demultiplexer 150 stores corresponding motion vectorsat positions allocated in the motion vector buffer 200 to the respectivelines based on inputted line number information.

The scroll detection unit 250 determines whether there exist scrollmotions of text, graphic data, or the like in a horizontal direction ina current field/frame based on the motion vectors stored in the motionvector buffer 200. Further, the scroll line detection unit 300determines whether there exist scroll motions with respect to individuallines in case that the scroll motions exist in the current field/frame.

FIG. 2 is a block diagram for showing in detail the line-wise motionestimation unit 100 of FIG. 1.

In FIG. 2, the motion estimation unit 100 is constructed with a pixelbuffer 101, an SAD buffer 103, an FIFO buffer 105, an motion detector107, a motion vector estimator 109, and an output selector 111.

The pixel buffer 101 sequentially inputs and stores pixels forming linesfor which motion vectors are calculated in a reference field/frame. TheFIFO buffer 105 sequentially inputs and stores pixels forming lines forwhich motion vectors are calculated in a current field/frame. The SADbuffer 103 stores summed absolute difference (SAD) values calculated byusing pixel data stored in the pixel buffer 101 and the FIFO buffer 105.The motion vector estimator 109 calculates motion vectors from the SADvalues stored in the SAD buffer 103. The motion detector 107 determinesthe validity of estimated motion vectors. Further, the output selector111 outputs motion vectors determined to be valid based on the validitydecision. If decided as invalid motion vectors, a certain constant constcan be outputted to notify of invalidity.

FIG. 3 is a flow chart for explaining an operation process for a motionestimation apparatus according to an embodiment of the presentinvention.

In the operation process of FIG. 3, first, the line-wise motionestimation unit 100 calculates an SAD value with respect to the i^(th)line in a specified search area based on a reference field/frame and acurrent field/frame (S300). In general, since scrolling text or graphicdata exists at the bottom of a screen, it is possible to enhance aprocessing speed by properly setting a search area instead ofcalculating SAD values over the entire field/frame.

SAD values in a search area are calculated through a process as below.First, the pixel buffer 121 stores pixel data constructing the i^(th)line of a reference field/frame, and the FIFO buffer 125 stores pixeldata constructing the i^(th) line of a current field/frame. The pixeldata for the reference field/frame and the current field/frame aresequentially inputted and stored till an SAD value for the i^(th) lineis completely calculated. The calculated SAD value is stored at acorresponding position in the SAD buffer 103. The SAD value iscalculated from following Formula 1.

$\begin{matrix}{{\Phi\left( {i,v} \right)} = {\sum\limits_{j = 0}^{N - 1}\;{{{f_{ref}\left( {i,{j - v}} \right)} - {f_{cur}\left( {i,{j + 1}} \right)}}}}} & {{Formula}\mspace{14mu} 1}\end{matrix}$

In here, ƒ_(ref)(i,j−ν) denotes pixel data positioned at a j−v column ofthe i^(th) line in a reference field/frame, and ƒ_(cur)(i,j+ν) pixeldata positioned at a j+v column of the i^(th) line in a currentfield/frame. As shown in Formula 1, an SAD value is calculated with vvalue changes, and the v corresponds to a motion estimation position.

If the calculation of the SAD value for the i^(th) line is completedthrough the above process, the motion vector estimator 109 estimates asthe motion vector a position having the minimum value out of the SADvalues stored in the SAD buffer 103 (S302). This is expressed in Formula2 as below.V=arg min Φ(i,ν)  Formula 2

The motion detector 107 determines the validity of a motion vector vestimated from the minimum and maximum values out of the SAD valuesstored in the SAD buffer 103 (S304). The motion vector is determined tobe valid if a difference between the minimum and maximum values of theSAD values is larger than a predetermined first threshold value Th1 asshown in Formula 3 as below. Otherwise the motion vector is determinedto be invalid.IF(max Φ((i,ν)−min Φ(i,ν))>Th1, the estimated motion vector is valid;ELSE the estimated motion vector is invalid.  Formula 3

The output selector 111 outputs a motion vector decided to be valid inthe motion detector 107, and stores the motion vector at a correspondingposition of the motion vector buffer 200 (S306). In this case, if theestimated motion vector is not valid, it may be possible that the outputselector 111 outputs a certain constant const to be stored. This may beexpressed in Formula 4 as below.vscr[i]=V  Formula 4in the above Formula 4, i denotes a line number, and vscr[i] a bufferallocated in the motion vector buffer 200 with respect to respectivelines.

After a motion vector for the i^(th) line is stored, it is decidedwhether the i^(th) line is the last line of an area set as a search area(S308), and, if the i^(th) line is not the last line, the above processis repeated up to the last line of the search line.

The scroll detection unit 250 estimates whether there exists on acurrent field/frame view a scroll motion of text, graphic data, or thelike from the motion vectors stored in the motion vector buffer 200(S310). The estimation of whether there exists the scroll motion oftext, graphic data, or the like follows a process as below.

First, the scroll detection unit 250 calculates the number ofoccurrences by magnitude with respect to motion vectors V stored in themotion vector buffer 200, and, if a predetermined number of occurrencesof motion vectors of certain magnitude appears, decides that the scrollmotion exists. That is, In case that scrolling text or graphic dataexists, some lines move in the horizontal direction at the same speed,so that a certain number of motion vectors of the same magnitude exist.

Through the above process, it is decided that there exist a scrollmotion on a current field/frame, the scroll detection unit 250 outputs a“1” as a scroll flag signal flag_scr (S312 and S314), and, otherwise,outputs a “0” for the scroll flag signal flag_scr (S312 and S314). Thisis expressed in Formula 5 as below.IF max hist[V]>Th2, flag_(—) scr=1 ELSE flag_(—) scr=0  Formula 5

In here, hist[V] denotes a histogram for motion vectors, and Th2 apredetermined second threshold value. The scroll flag signal flag_scroutputted from the scroll detection unit 250 may be used as a signal forexternal devices that indicates whether the scroll motion exists.

The scroll line detection unit 300 estimates whether scrolling text orgraphic data exists line by line in a search area in case that thescrolling text or graphic data exists (S316).

The decision on the scroll motion for each line is made by whether themotion vector estimated line by line corresponds to a motion vector overthe certain number of occurrences used when the scroll detection unit250 determines whether the scroll motion exists. If it is decided thatscrolling text or graphic data is included in a corresponding linethrough such a determination process, the scroll line detection unit 300outputs “1” for a corresponding scroll line flag flag_scr_line[i], and,otherwise, outputs a “0” for the corresponding scroll line flagflag_scr_line[i]. Such a process is carried out for all the lines in asearch area, so it is determined whether scroll motions exist line byline.

The motion vectors, scroll flag flag_scr, and scroll line flagflag_scr_line[i] calculated by the above process may be used for IPCmethods. For example, as to an area in which scroll motions exists,information such as the motion vectors, scroll flag flag_scr, and scrollline flag flag_scr_line[i] calculated by the above process is used forimage interpolations, and, for other areas, an IPC method of appropriatemode is used for image interpolations. Through such a process, betterquality images and an improved processing speed can be obtained,compared to a case that image interpolations are carried out withoutconsideration of scrolling text or graphic data.

As described above, the present invention can detect by a relativelysimple method whether text or graphic data scrolling in a horizontaldirection on a screen exists. Further, the present invention alsoprovides information, such as motion vectors and the like, which isrelated to scrolling text or graphic data and can be used for imageinterpolations, enabling image interpolations advantageous in aspects ofimprovements of image quality and processing speed.

The hardware included in the system may include memories, processors,and/or Application Specific Integrated Circuits (“ASICs”). Such memorymay include a machine-readable medium on which is stored a set ofinstructions (i.e., software) embodying any one, or all, of themethodologies described herein. Software can reside, completely or atleast partially, within this memory and/or within the processor and/orASICs. For the purposes of this specification, the term“machine-readable medium” shall be taken to include any mechanism thatprovides (i.e., stores and/or transmits) information in a form readableby a machine (e.g., a computer). For example, a machine-readable mediumincludes read only memory (“ROM”), random access memory (“RAM”),magnetic disk storage media, optical storage media, flash memorydevices, electrical, optical, acoustical, or other form of propagatedsignals (e.g., carrier waves, infrared signals, digital signals, etc.),etc.

Although a few embodiments of the present invention have been shown anddescribed, it will be understood by those skilled in the art thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the present invention as definedby the appended claims and their equivalents.

1. A motion estimation apparatus, comprising: a line-wise motionestimation unit for calculating motion vectors indicating the extent ofmotions in a horizontal direction for individual lines of apredetermined search area with reference to a current field/frame and areference field/frame; a motion vector buffer for storing motion vectorsfor the individual lines; a scroll detection unit for determiningwhether scroll motions exist in the current field/frame based on themotion vectors for the individual lines which are stored in the motionvector buffer; a scroll line detection unit for determining whether thescroll motions exist in the individual lines of the search area, basedon a result of the determination of the scroll detection unit; and ademultiplexer to store corresponding motion vectors at positionsallocated in the motion vector buffer to respective lines based oninputted line number information.
 2. The motion estimation apparatus asclaimed in claim 1, wherein the line-wise motion estimation unitincludes: a pixel buffer for sequentially storing pixel dataconstructing lines to calculate the motion vectors in the referencefield/frame; a FIFO buffer for sequentially storing pixel dataconstructing lines to calculate the motion vectors in the currentfield/frame; an SAD buffer for calculating and storing summed absolutedifference (SAD) values based on estimations of the extent of motions,using the pixel data respectively stored in the pixel buffer and theFIFO buffer; and a motion vector estimator for calculating the motionvectors based on the SAD values stored in the SAD buffer.
 3. The motionestimation apparatus as claimed in claim 2, wherein the motion vectorestimator calculates the motion vectors in correspondence to a motionestimation position having the minimum value of the SAD values stored inthe SAD buffer.
 4. The motion estimation apparatus as claimed in claim2, further comprising: a motion detector for determining the validity ofthe motion vectors calculated by the motion vector estimator; and anoutput selector for selectively outputting only selected motion vectorsbased on a result of the validity decision of the motion detector. 5.The motion estimation apparatus as claimed in claim 4, wherein themotion estimator determines that the motion vectors are valid if adifference between the maximum value and the minimum value of the SADvalues stored in the SAD buffer is larger than a predetermined thresholdvalue.
 6. A motion estimation apparatus, comprising: a line-wise motionestimation unit for calculating motion vectors indicating the extent ofmotions in a horizontal direction for individual lines of apredetermined search area with reference to a current field/frame and areference field/frame; a motion vector buffer for storing motion vectorsfor the individual lines; a scroll detection unit for determiningwhether scroll motions exist in the current field/frame based on themotion vectors for the individual lines which are stored in the motionvector buffer; and a scroll line detection unit for determining whetherthe scroll motions exist in the individual lines of the search area,based on a result of the determination of the scroll detection unit,wherein the scroll detection unit calculates a number of occurrences ofa plurality of magnitudes of the motion vectors stored in the motionvector buffer, and determines that the scroll motions exist when motionvectors of certain magnitudes are determined to be more than apredetermined number of occurrences.
 7. The motion estimation apparatusas claimed in claim 6, wherein the scroll line detection unit determinesthat the scroll motions exist in corresponding lines when motionvectors, calculated line by line, correspond to the magnitudes of motionvectors determined to be more than the predetermined number ofoccurrences.
 8. A motion estimation method, comprising: (a) calculatingmotion vectors indicating the extent of motions in a horizontaldirection for individual lines of a predetermined search area withreference to a current field/frame and a reference field/frame; (b)storing motion vectors for the individual lines; (c) determining whetherscroll motions exist in the current field/frame based on the storedmotion vectors for the individual lines; (d) determining whether thescroll motions exist in the individual lines of the search area, basedon a result of the determination of operation (c); and (e) storingcorresponding motion vectors at positions allocated to respective linesbased on inputted line number information.
 9. The motion estimationmethod as claimed in claim 8, wherein operation (a) further comprises:(a1) sequentially storing pixel data constructing lines to calculate themotion vectors in the reference field/frame; (a2) sequentially storingpixel data to calculate the motion vectors in the current field/frame;(a3) calculating and storing summed absolute difference(SAD) valuesbased on estimations of the extent of motions, using the pixel datarespectively stored in the operations (a1) and (a2); and (a4)calculating the motion vectors based on the stored SAD values.
 10. Themotion estimation method as claimed in claim 9, wherein the operation(a4) calculates the motion vectors in correspondence to a motionestimation position having the minimum value of the stored SAD values.11. The motion estimation method as claimed in claim 9, furthercomprising: determining the validity of the motion vectors calculated inthe operation (a4); and selectively outputting only valid motion vectorsbased on a result of the validity determination.
 12. The motionestimation method as claimed in claim 11, wherein the determining thevalidity determines the motion vectors as valid if a difference betweenthe maximum value and the minimum value of the SAD values stored in aSAD buffer is larger than a predetermined threshold value.
 13. A motionestimation method, comprising: (a) calculating motion vectors indicatingthe extent of motions in a horizontal direction for individual lines ofa predetermined search area with reference to a current field/frame anda reference field/frame; (b) storing motion vectors for the individuallines; (c) determining whether scroll motions exist in the currentfield/frame based on the stored motion vectors for the individual lines;and (d) determining whether the scroll motions exist in the individuallines of the search area, based on a result of the determination ofoperation (c), wherein operation (c) calculates the number ofoccurrences of a plurality of magnitudes of the stored motion vectors,and determines that the scroll motions exist when motion vectors ofcertain magnitudes are determined to be more than a predetermined numberof occurrences.
 14. The motion estimation method as claimed in claim 13,wherein operation (d) determines that the scroll motions exist incorresponding lines when motion vectors, calculated line by line,correspond to the magnitudes of motion vectors determined to be morethan the predetermined number of occurrences.
 15. The motion estimationapparatus of claim 4, wherein, if the motion detector determines that amotion vector is invalid, the output selector outputs a constant toindicate invalidity.
 16. The motion estimation method of claim 11,further comprising: if a motion vector is invalid, outputting a constantto indicate invalidity.
 17. A machine-readable medium that providesinstructions, which, when executed by a machine, cause the machine toperform motion estimation operations comprising: (a) calculating motionvectors indicating the extent of motions in a horizontal direction forindividual lines of a predetermined search area with reference to acurrent field/frame and a reference field/frame; (b) storing motionvectors for the individual lines; (c) determining whether scroll motionsexist in the current field/frame based on the stored motion vectors forthe individual lines; (d) determining whether the scroll motions existin the individual lines of the search area, based on a result of thedetermination of operation (c); and storing corresponding motion vectorsat positions allocated to respective lines based on inputted line numberinformation.
 18. The machine-readable medium of claim 17, wherein theinstructions cause the machine to perform motion estimation operationsfurther comprising: (a1) sequentially storing pixel data constructinglines to calculate the motion vectors in the reference field/frame; (a2)sequentially storing pixel data to calculate the motion vectors in thecurrent field/frame; (a3) calculating and storing summed absolutedifference(SAD) values based on estimations of the extent of motions,using the pixel data respectively stored in operations (a1) and (a2);and (a4) calculating the motion vectors based on the stored SAD values.19. The machine-readable medium of claim 18, wherein operation (a4)calculates the motion vectors in correspondence to a motion estimationposition having the minimum value of the stored SAD values.
 20. Themachine-readable medium of claim 18, wherein the instructions cause themachine to perform motion estimation operations further comprising:determining the validity of the motion vectors calculated in operation(a4); and selectively outputting only valid motion vectors based on aresult of the validity determination.
 21. The machine-readable medium ofclaim 20, wherein the determining the validity determines the motionvectors as valid if a difference between the maximum value and theminimum value of the SAD values stored in a SAD buffer is larger than apredetermined threshold value.
 22. A machine-readable medium, thatprovides instructions, which, when executed by a machine, cause themachine to perform motion estimation operations comprising: (a)calculating motion vectors indicating the extent of motions in ahorizontal direction for individual lines of a predetermined search areawith reference to a current field/frame and a reference field/frame; (b)storing motion vectors for the individual lines; (c) determining whetherscroll motions exist in the current field/frame based on the storedmotion vectors for the individual lines; and (d) determining whether thescroll motions exist in the individual lines of the search area, basedon a result of the determination of operation (c), wherein operation (c)calculates a number of occurrences of a plurality of magnitudes of thestored motion vectors, and determines that the scroll motions exist whenmotion vectors of certain magnitudes are determined to be more than apredetermined number of occurrences.
 23. The machine-readable medium ofclaim 22, wherein operation (d) determines that the scroll motions existin corresponding lines when motion vectors calculated line by linecorresponds to the magnitudes of motion vectors are determined to bemore than a predetermined number of occurrences.